Call distributing system



Sept. 12, 1939. POWELL CALL DISTRIBUTING SYSTEM 1 2 Sheets-Sheet 1 Filed Nov. 10, 1937 Pol 1040 me av Y a wE INVENTOR WINFRED T. POWELL BY A - ATTORN Y Sept. 12, 1939. w. T. POWELL 2,172,805

I CALL DISTRIBUTING SYSTEM Filed Nov. 10, 1957 2 shee ts sheat '2 g t g I 3 RED LAMPs A v 3 I move-non POSITION 1 con. RELAY comma TO ALL POSITIONS 0 A GROUP.

INVENTOR WINFRED T. POWELL ATTORNEY Patented Sept. 12, 1939 UNITED STATES PAT ENT OFFICE GALL DISTRIBUTING SYSTEM tion of New York Application November 10, 1937, Serial No. 173,796

6 Claims.

This invention relates to a telephone system and more particularly to a call distributing system.

In accordance with the present invention it is proposed to distribute calls from a plurality of exchanges to the B operators in succession at a given exchange and means are provided for assigning one call in addition to the call being answered at'a position when all the positions of a group at said exchange are engaged in handling a call. By this arrangement one call and one call only is awaiting attention while a given B operator is engaged in completing a previous call even during busy periods.

The drawings with Fig. I placed above Fig. 2 diagrammatically represent a portion of a telephone system wherein a calling telephone line and an A operators cord circuit at a distant exchange are shown at the left of the vertical dotted 20 line in Fig. 1; the portion of this figure at the right of this dotted line as well as all of the equipment shown in Fig. 2 are located at a distant oifice having B operators positions for completing calls; the portion of the circuit arrangement 25 illustrated in the upper righthand corner of Fig. 1 illustrates a primary selector and a secondary selector for selecting a B operators position equipped with a cord circuit, this circuit has not been completely shown nor has the called 30 telephone line been illustrated; the portion of Fig. 1 below the horizontal broken line illustrates the equipment common to a group of primary and secondary selectors.

It will be understood that the A operators at 35 several distant exchanges are provided with jacks, which jacks may be arranged in groups and connected by incoming trunks to a group of primary selector switches having access to secondary switches, which select B operators positions. By Way of example, it is assumed, that there are 400 incoming trunks from the various distant exchanges and since each trunk terminates in a primary selector there will be 400 of these primary selectors. It is preferred to ar- 5 range these primary selectors into ten groups so that there will be 40 primary selectors in each group. The secondary selector switches are likewise divided into ten groups, but since there are only 240 outlets leading to the 240 B trunks from 50 the secondary selectors, there are only 24 secondary selectors in each group or a total of 240 secondary selector switches. The primary and secondary selectors herein disclosed are preferably of the twenty five point rotary type which 55 remainin the position last used.

It is believed that the invention will best be understood by describing the operations involved in establishing a telephone call from a subscribers substation telephone as A terminating at one ofiice, to a B operators position located at a' distant office. When the subscriber'at substation A originates a call by removing his receiver from its switch hook, the line relay 5 is energized over the two sides of the calling subscribers line in series, back contacts and armatures of cut off relay 6, the windings of the line relay 5, to grounded battery and to ground respectively. This energizes the line relay which attracts its armature to light the line lamp 1 associated with the jack J of the calling subscribers line. The operator at the position where the jack J is located, selectsa cord circuit C and inserts the answering plug P thereof into the jack J. .The insertion of the'plug P into the jack J completes a circuit for energizing cut off relay 8 from ground, winding of this relay, sleevecontacts of the jack and plug, conductor 8, winding of the relay 9 to grounded battery. Cut off relay 6 when energized, opens the previously described circuit for line relay 5 which deenergizes to extinguish the line lamp 1. The relay 9 on energization, closes a break point in the circuit'for lighting the supervisory lamp Hi. This lamp is not lighted at this time, since the supervisory circuit is not open at the armature and back contact of the supervisory relay II, which is energized over the answering end of the cord circuit C and the two sides of the calling line in series. Immediately after the operator inserts the plug P into the jack J she operates the listening key LK of the cord circuit in use to connect her head set l2 to this circuit and requests the number of the wanted line.

On receiving this information, the operator inserts the plug P at the calling end of the cord circuit G into the jack J of a trunk connected to the wanted office. As soon as this operation is completed, the relay l3 associated with the primary selector switch PS of the selected trunk is operated in a circuit traceable from ground battery, righthand winding of the supervisory relay M, the lower sideof the calling end of the cord circuit C, ring contacts of the plug P, jack J, inner, upper, back contact of relay [5, through the lefthand, high resistance winding of the relay 13, upper back contact and armature of relay I5, tip contacts of the jack J and the plug P, upper side of the cord circuit C, lefthand winding of relay I4 to ground. Relay [4 does not energize in series with relay l3 to permit the lighting of the calling supervisory relay at this time. Relay I3 is energized, completing an energizing circuit for the slow releasing relay 25 from grounded battery, winding of this relay, armature and front contact of relay I3, outer right hand back contact of relay 25, lefthand winding of common relay 24 to ground. The relay 25 is thus energized to attract its armatures but the relay I5 will not be energized as will be pointed out until an idle trunk is located. If the trunk being tested is busy, the slow releasing relay 25 will now have a locking circuit completed for itself from grounded battery, its winding, armature and front contact of relay l3, front contact and armature of relay 25, thence thru the lower winding of relay l5, back contact and lower armature of relay l5, primary selector test brush 26, test terminal 21., which terminal has ground potential thereon, this ground potential being applied through a test brush such as 26,-

lower armature and front contact to ground at a switching relay such as l5 associated with a primary selector that has previously seized this trunk. Relay l5 will not be operated in this last described circuit since its upper and lower windings are energized in opposition. If the brushes of the primary selector switch P8 are resting on the terminals of an idle trunk, the switching relay I5 will be immediately energized and at its upper front contacts and armatures, extends the tip'and ring trunk conductors and 2! through the brushes 22 and 23 to an idle secondary selector SS. The circuit for operating the switching relay l5 extends from ground, lefthand wind- 1 ing of the relay 24, upper winding of the relay l5, outer front contact and armature of the relay 25, lower winding of relay l5, inner front contact and armature of relay 25, armature, back contact and winding of the motor magnet 32, righthand winding of relay 24 to grounded battery. It should be noted that the windings of relay 55 are energized at this time in a direction to aid each other. When the switching relay is energized, it closes its lower front contacts and armature and at its lowermost armature and 4 front contact, applies ground potential through the test brush 26 of the primary selector to the terminal 2'! of the selected secondary trunk on which the primary switch brushes are resting. It willbe understood that the presence of ground potential on the multiple terminals 21, makes this trunk test busy to other primary selectors.

When the primary trunk has thus been selected and the switching relay [5 has been operated, the rela 28 associated with the primary trunk is energized over the two sides of this trunk, the brushes 22 and 23 of the primary selector and over the two sides of the incoming trunk through the windings of the supervisory relay E4 in series at the cord circuit C, and thence to ground and grounded battery respectively. As soon as high resistance relay 28 is thus energized, it causes the energization of the slow releasing relay 29 in a circuitextending from grounded battery, winding of relay 29, conductor 35, armature and front contact of relay 28, continuity spring and back contact of relay 29, conductor 3!, lefthand winding of the common alarm relay 34 to ground. Relay 29 will be locked operated in a circuit arrangement substantially identical with that of slow releasing rela 25, previously described.

With the switching relay l5 and the slow releasing relay 29 both operated, the slow releasing relay 25 of the primary selector switch is noW held operated from grounded battery, winding of this relay, inner lower front contact and arma ture of relay 55, holding brush 33 of the primary selector, inner lefthand front contact and armature of relay 29, test terminal 27, test brush 26 of the primary selector, lowermost armature and front contact of relay l5 to ground. The ground at the lowermost front contact and armature of the switching relay i5 is applied through the test brush of the primary selector to the multiple terminals 27 of the primary trunk as long as this trunk is engaged so that it cannot be seized by another primary selector.

If the brushes of the primary selector were in engagement with the terminals of a busy primary runk when the relays l3 and 25 at the primary selector were energized in response to the insertion of the plug P into the jack J, the primary selector would immediately start to hunt for an idle primary trunk, since, as described above, switching relay l5 does not operate at this time but the slow releasing relay 25 is held operated. The stepping circuit of the primary selector extends from grounded battery, righthand winding of the relay 24, winding, back contact and armature of the motor magnet 32 of the switch, inner armature and front contact of relay 25, lowermost back contact and armature of the switching relay l5, primary selector test brush 26 and grounded multiple terminals such as 21 of busy primary trunks. It will be recalled that ground on the test terminal such as 2? of busy primary trunks is applied thereto through a test brush such as '25 of a primary selector that has previ ously seized this trunk, and through the lowermost armature and front contact to ground at the switching relay such as l5 of that switch. As long as the test brush 2% of the primary selector of the present connection encounters busy terminals 2?, the circuit for the motor magnet 32 will be completed in the manner described and this motor magnet will interrupt its own circuit to advance the primary switch brushes until an idle trunk is reached. At this time the switching relay l5 will be energized in the manner already described and will be maintained energized as long as the connection is established.

When the idle trunk has been seized, e. g. that shown in the upper portion of Fig. 1, the relay 28 and the slow releasing relay 29 will be energized as previously described. If the brushes 35 and 38 inclusive are resting on the terminals of an idle B cord circuit, the switching relay 40 will be energized in a circuit identical with that described for the switching relay P5 of the primary selector. However, if the secondary selector brushes are resting on the terminals of a busy secondary trunk when this switch is seized, an operating circuit for the motor magnet ii of this switch is closed to grounded battery, righthand winding of the alarm relay 3 4, winding of the motor magnet 4!, its back contact and armature, inner armature and front contact of relay 29, lowermost back contact and armature of relay 49, test brush 38 and the grounded terminal 39 of busy cord circuits. As long as the test brush 38 encounters busy test terminals 39, this circuit for the motor magnet is completed and the motor magnet interrupts its own circuit to step the brushes of the secondary selector until an idle B cord circuit is located, the test terminal of which will be characterized by the absence of ground potential thereon. As soon as this idle B cord circuit is located, the switching relay 40 will be operated in the same manner as switching relay 45 previously described, and will extend the connection from the supervisory relay 14 in the originating cord circuit over the two sides of the connection thus far established, through both windings in series of the relay 43, individual to the selected cord circuit. The energization of the relay 43, energizes the relay 44 which in turn energizes the relay 45. The relay 45, at its front contact and armature, extends ground through the holding brush 5'! of the secondary selector, inner front contact and armature of the switching relay 4!], conductor 35, winding of the relay 29, to grounded battery. This ground holds relay 29 after relay 28 is released by the opening of the upper back contacts of relay 40.

The B cord circuit may be substantially the same as that disclosed in Figs. 6 and 7 of applicants Patent #1,861,754, granted June 7, 1932, from which patent, it will be understood that as soon as the B cord circuit is selected, the B operator will receive the wanted station designation from the A operator and will complete the connection to the wanted subscriber in the manner therein set forth.

Since the number of primary trunks or outlets is greater than the number of secondary trunks or outlets into which calls are distributed, it is possible for all of the secondary trunks of a group of secondary switches to be in use while there still remain a number of primary selectors in this group which are not being used. In other words, when the twenty four primary selectors of any group are in use, all of the available outlets or trunks of this group are engaged but there are still 16 additional outlets from A operators position associated with this group which are not in use. Because of this condition, it becomes necessary to indicate to an A operator, that all of the outlets of a given group of primary selectors are busy. In order to effect this result, there is provided, a tone relay 41 at the lower part of Fig. 1, which relay is energized when all of the secondary selectors associated with a particular group of primary outlets are busy. This relay is energized by a circuit extending from grounded battery, winding of this relay and through the outer lefthand contacts and armatures in series of the relays similar to 29 to ground at the last of such relays in the series. When all of these relays of the group are actuated so that the tone relay 4'! is thus energized, it completes at its front contact and armature a connection toa tone source. This tone is induced through the transformer 48 into the circuit including the multiple conductors 49 connected in series with the righthand windings of the relays l3. At these windings, the tone is induced into the lefthand winding of relays l 3 of the group and is communicated through the upper back contacts and armatures of relays [5 to the jacks such as J. Thus if the operator plugs into a jack connected to a primary selector which cannot find an idle secondary trunk in this group she will immediately hear the group busy tone in her headset which will be a signal to her to plug the cord circuit in use into an outlet leading into another group.

Since all trunks leading to each B operators position are made busy during the time that the B operator thereat is engaged in handling a call, it also becomes necessary to prevent the selection of this B position by any secondary selector while this busy condition exists. Furthermore,

it may happen that all the outlets from a secondary selector group are made busy due to the above condition so that the secondary switches associated with such a group must be made to test busy. This is accomplished by the common connection to the inner lefthand back contact and armature of relays such as 29. When all outlets of a particular secondary group are busy, all of the associated make busy relays 50 of this group will be energized for completing a series circuit to the common conductor which leads thru the back contacts of all of the relays such as 29 of all secondary switches having access to the last make busy relay 50 of the series. This series circuit is extended through the mentioned back contacts of relays such as 29 to the test terminals such as 2? of these secondary switches, so that they cannot be selected by a primary selector switch.

Thus a system is provided whereby calls are normally distributed one at a time to idle B operator positions as long as there is at least one B position idle. However in accordance with the present invention, when all B positions are busy, one additional call only is permitted to be assigned to each position, and there await its turn so that during periods of heavy traflic, one waiting call is distributed to each of the various B positions of the group. It will be understood that such waiting calls will immediately take their turn inthe sequence cut-in circuit and will be automatically connected to a B operator's circuit just as soon as the previous call is disposed of. The arrangement for accomplishing this result is shown mainly in Fig. 2 which indicates the relays common to each position together with a relay 52 which is common to all positions.

It will be recalled that the switching relay 40 is energized for extending an incoming trunk circuit through primary and secondary trunks to the selected B cord circuit and that relays 43, 44 and 45 operate in sequence after the B trunk is selected. The application of ground potential to the terminal such as 39, as a result of the operation of the relay 40, immediately makes all of the idle trunks leading to this particular B operators position busy. This takes place since the ground potential on the test terminal 39 applied by the switching relay 48, is extended through the lower armature and back contact of relay 45 to the common conductor 53 and thence through similar back contacts and armatures of relays such as 45 at this B operators position to the corresponding terminals tested by any secondary selector test brush such as 38 so that all of these trunks will test busy. Before the relay 45 operates to open this common circuit including conductor 53, the relay 54 (lower right corner of Fig. 2) is energized in a circuit traceable from a ground, winding of this relay, conductor 55, inner back contact and armature of relay 45, holding brush 3?, inner armature andfront contact of switching relay 48, conductor 39, winding of relay 29 to grounded battery. Relay 54 is thus energized and at its upper armature and front contact also applies ground potential to the common conductor 53. As soon as relay 54 energizes, it eifects the operation of slow releasing relay 56 in a circuit extending from grounded.

battery, lower Winding of this relay, lower front contact and armature of relay 54 to ground. Relay 56, at its uppermost armature and front contact, also applies ground potential to the mentioned common conductor 53. As soon as relay 45 operates, it interrupts the energizing circuit of relay 54 causing it to release. But since the relay 56 is slow releasing, it holds ground potential on the common conductor 53 until the operators cut-in circuit in the B cord circuit (not shown) functions and operates relay .5! as shown in the mentioned patent. Relay 5'! may operate in the same manner as r-elay H of the mentioned patent. As soon as the relay 5'! is operated, it effects the energization of the make busy relay 58 in a circuit traceable from grounded battery, lower winding of this relay, armature and front contact of relay El to ground. Relay 58 also extends ground potential from the back contact and armature of the common relay 52, conductor 59, upper front contact and armature of relay 58, front contact and armature of relay G0, which is energized as long as the B operator is at her position, thence to the common conductor 53. Relay 5'. maintains the position make busy relay 58 energized until the operator becomes idle, at which time the release of the relay 5? and in turn the release of the relay 58 removes the ground potential from the common conductor 53, which removes the busy condition from the B trunks associated therewith. This same operation is likewise effected for other circuits at other positions.

It will now be explained how this position busy circuit is operated and released when all positions are busy handling calls. With all positions busy, make busy relays such as 58, 58a, 58b, etc. are energized which indicates that a call is being handled at each position, a chain circuit is completed for energizing the common relay 52. This chain circuit, which is not effective until the relay such as 5% at each position is released, is traceable from grounded battery, winding of the common relay 52 and through the front contacts and armatures of the position make busy relays 58 of the group and through the back contacts and armatures of the relays 56 of the group to the ground at the last relay 56 of the series. When the common relay 52 is energized, it is locked in this condition from grounded battery, its winding, front contact and armature and thence through the front contacts and armatures of all relays such as 53 of the series to ground at the last relay 58 of the series. With the common relay 52 energized, a relay such as 55, which operated and then released to establish the all position busy condition, is energized again on the receipt of the next incoming call at the associated position in the same manner as previously described. The reason that the B positions are not made busy under the conditions just described, is that the ground potential connections for busying all trunks at each 13 operators position are opened at the back. con tacts of the common relay 52, however, when the next call comes into a busy position and its relays such as end 55 are operated as before, the relay 55 is locked operated over a circuit completed from ground at its uppermost armature and front contact, front contact and armature of the induction coil relay 60, front contact and armature of relay 58, conductor 59, armature and front contact of armature of common 52, inner upper armature and front contact and winding of relay 55 to grounded battery. It will thus be seen that a second call is permitted to be in Waiting at each position when all positions are busy handling a call. A red lamp 62 is connected in multiple with the locking winding of each relay 56, which lamp when lighted serves as an indication to the B operator that a call is waiting at her position for the completion of the preceding call which she is handling. This red lamp indication then serves to speed up the operation during busy periods.

It will be understood that the ground potential applied through the uppermost armature and front contact of relay 56 extends over the common wire 53 for making all trunks at the associated position busy when a call is awaiting attention at this position. Since this ground is not removed until the first call in the process of completion is disposedof, the associated B position is held busy as long as a second call is awaiting attention thereat. When the relay 5? of the B cord circuit in use in completing the first call, releases, it effects the deenergization of the relay 58. When this last relay releases, the chain circuit is opened to effect the release of the common relay 52. As a result of this, the waiting call is immediately permitted to cut into the sequence circuit for operating the operators cut in circuit (not shown) at the B operators circuit now in use. If at this time, all other positions are busy, then the chain circuit is again effective to operate the common relay 52 and another call can be received and await attention at this same position. It will thus be seen that it requires the release of the relay 51, which is energized during the completion of the call at its B trunk circuit and a consequent release of its associated relay 58 in order to place the call awaiting feature in its normal condition.

It will be noted that a baring key 53 is illustrated at the righthand side of Fig. l, which key is associated with each B trunk circuit so that individual trunk circuits at the B position can be made busy as desired. In addition, there is illustrated in the upper righthand corner of Fig. 2, an induction coil relay 6!]. This relay is energized as long as the operators head set is plugged in, and is for the purpose of automatically rendering a B operators position busy when her telephone set is disconnected.

In the lower portion of Fig. 1, there are illustrated alarm relays 24 and 34 which are effective to give an alarm when the primary or secondary selector switch magnets, such as 32 or M, fail to operate properly. The dash pot relays 64 and 65 respectively associated with the alarm relays 24 and 34 are slow to energize so that in the normal operation of these magnets, these dash pot relays fail to operate. If, however, there is a failure on the part of the magnets 32 or 41, its related dash pot relay will operate to give an alarm so that an attendant can correct the difficulty.

I claim:

1. In a call distributing system, a group of operators positions, means including primary and secondary switches for distributing calls one at a time to said positions, said primary switches be" ing greater in number than said seconc switches, a trunk leading to each primary swi means for applying a busy indication to trunks not in use, when all of said secondary swit es are taken for use, and means including said switching means for assigning a second call only to each of said positions when said group oi tions are each engaged in extending a first 2. In a call-distributing system a group of operators positions, each position having means to extend calls therefrom, means including primary and secondary switches for distributing calls to said positions, said primary switches being greater in number than said secondary switches, a trunk leading to each primary switch, means for normally rendering each position unselectable until a call distributed thereto has been extended, means for applying a busy indication to trunks not in use when all of said secondary switches are taken for use, means for directing a second call to each of several of said positions while all of said positions are each engaged in extending a first call, and means for cutting-in the directed call at a given position when the first call thereat has been extended.

3. In a call-distributing system, a group of op erators positions, each position having means to extend calls therefrom, means including primary and secondary automatic switches for distributing calls to said positions, said primary switches being greater in number than said secondary switches, a trunk leading to each primary switch, means for normally rendering each position unselectable until a call distributed thereto has been extended, means for applying a busy indication to trunks not in use when all of said secondary switches are taken for use, means including means common to said positions for directing a second call to each of said positions, means at all of said positions operated in response to the operation of extending calls therefrom for jointly rendering said common means efiective, and means for cutting-in a given directed call to the given position when the first call thereat has been extended.

4. In a call distributing system, a group of trunks terminating at each position, means including automatic switches for distributing calls to said trunks, test terminals in said switches for each of said trunks, a multi-branch circuit for temporarily applying a busy condition to all of said terminals of a group of trunks responsive to the selection of one of the trunks in said groups, a second multi-branch circuit including at least a position of said first circuit for maintaining the busy condition on said test terminals until said selected trunk is extended, a relay common to said groups of trunks for completing said second circuit, means including a chain circuit for controlling said common relay to open the second circuit whereby a second trunk in each group can be selected before a first selected trunk is extended, said chain circuit being completed responsive to the use of a trunk in each group in extending a call, and means for cutting in a second selected trunk in a group when said first trunk in said last-mentioned group has been extended.

5. In a call distributing system, a group of operators positions, each position having means to extend calls therefrom, means including automatic switches for distributing calls to said positions, means for normally rendering each position unselectabl-e until a call distributed thereto has been extended, means including a relay common to all of said positions for directing a second call to each of said positions, a chain circuit for operating said relay, said chain circuit having a break point therein at each position, means responsive to the use of a given position in extending a call for closing the break point thereat, and means for cutting in a given directed call to the position to which it has been directed when the first call thereat has been extended.

6. In a call distributing system a group of operators positions, a group of trunks terminating at each position, means for extending calls from said positions, means including automatic switches for distributing calls to said positions, test terminals in said switches for each of said trunks, a multi-branch circuit for temporarily applying a busy condition to all of said terminals of a group of trunks responsive to the selection of one of the trunks in said groups, a second multi-branch circuit including at least a position of said first circuit for maintaining the busy condition on said testterminals until said selected trunk is extended, a relay common to said positions for completing said second circuit, means including a chain circuit for controlling said common relay to open said second circuit whereby a second trunk at each position can be selected before a first selected trunk thereat is extended, said chain circuit being completed responsive to the use of a trunk at each position in extending a call, and means for cutting in a second selected trunk to the position at which it terminates when said first trunk thereat has been extended.

WINFRED T. PO'W'EIL. 

